Abstract: Nano-Fe₃O₄ is a kind of nano-materials with the excellent magnetic properties.The basic properties and applications of nano-Fe₃O₄ were introduced in this paper.The principles, research status, advantages and disadvantages, and development trends of nano-Fe₃O₄ preparation technology were reviewed, such as precipitation method, hydrothermal method, microemulsion method, and sol-gel method.It was pointed out that nano-Fe₃O₄ with more excellent properties could be prepared by the combination of various preparation technology